Heat management is important in light sources, in particular when solid state light emitters like Light Emitting Diodes (LEDs) are used as light emitter. LEDs generate on a relatively small area a relatively large amount of light and a relatively large amount of heat that must somehow be conducted towards the environment. When a LED becomes too hot, the LED may become permanently damaged resulting in a non-functional light source. Several solutions have been proposed like providing thermal paths via heat conductive materials towards a heat sink (which comprises, for example, cooling fins).
Published patent application US2008/0150126, which is incorporated by reference, discloses a Light Emitting Diode (LED) module with a heat dissipation device. The heat dissipation device includes a plurality of heat spreaders each supporting at least one LED, includes a base that supports the heat spreaders and includes a heat pipe sandwiched between the base and the heat spreader. The heat spreaders are thermally connected together via the heat pipe.
The heat dissipation device according to the cited prior art spreads the heat generated in the LEDs locally with the heat spreaders and uses the heat pipe to spread the heat along a larger space. The base is, for example, a heat sink with cooling fins. The heat dissipation device provides heat spreading such that the temperature of the LEDs is not becoming too high. The cooling capacity of the heat dissipation device is limited by the amount of heat that can be transferred between the different elements (LED-heat spreaders-heat pipe-base) and, finally, to the environment. Furthermore, the cooling capacity of the base strongly depends on manufacturing limitations of such a base—for example, with known manufacturing technologies like extrusion or molding it is almost impossible to manufacture cooling fins that provide an optimum between a size of a surface in contact with the environmental air, conduction of heat by the fins, and space for environmental air to flow through the cooling fins. Thus, the heat dissipation device is capable of cooling LEDs, but has also limitations in its cooling capacity.
There is a tendency to increase the power of the LEDs and the heat dissipation device of the cited patent application lacks cooling capacity for such high power LEDs.